Abstract

A lack of dependence of the Raman frequency of optical vibrational modes on excitation wavelength in polar nanosemiconductors was observed. This is in contrast to the earlier observed dependence in nonpolar nanomaterials: carbon nanotubes and Si nanowires. This difference has been ascribed to the different crystallographic natures of their Raman spectra: crystalline for nonpolar and amorphous for polar nanosemiconductors. The result has been explored theoretically to the Raman spectra being insensitive to sample sizes and thus indicates that the size confinement effect, a basic effect in nanomaterials, does not exhibit in the optical vibrational modes of polar nanosemiconductors.

Received 14 January 2006Accepted 02 July 2006Published online 08 August 2006

Acknowledgments:

The authors acknowledge the support from the NSFC under Grant Nos. 60290083, 50334040, and 50272017, and RGC of Hong Kong under Grant No. 401003, as well as from the State Key Laboratory for Inferred Physics and the Beijing Key Laboratory for Nano-Photonics and Nano-Structure. The author thank the Nano-Chemical Group of Peking University for technical assistance, Shou Shan Fan for providing samples, and K. T. Yue and S. K. Hark for their help in writing.